<!DOCTYPE html>
<html>
    <head>
        <script src="vue.js"></script>
    </head>
    <body>
        <div id="app">
            <input type="text" v-focus="true">
        </div>
        <script>
            Vue.directive('focus',{
                inserted(el,binding){
                    if(binding.value){
                        el.focus();
                    }
                }
            })
            var vm = new Vue({
                el:'#app'
            });
        </script>
    </body>
</html>